Process for producing a concentrated coffee extract

ABSTRACT

Provided is a concentrated coffee extract solution having a rich sweet aroma and a clear aftertaste. The concentrated coffee extract solution contains the following components (A) and (B):
         (A) at least one pyrazine selected from 2-methylpyrazine, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, ethylpyrazine, 2-ethyl-5-methylpyrazine, 2-ethyl-6-methylpyrazine, 2-ethyl-3-methylpyrazine, 2-ethyl-3,5-dimethylpyrazine and 3,5-dimethyl-2-methylpyrazine, and   (B) at least one guaiacol selected from guaiacol, 4-ethylguaiacol and 4-vinylguaiacol. A content weight ratio [(B)/(A)] of the component (B) to the component (A) is 0.6 or smaller.

This application is a divisional of U.S. application Ser. No. 13/318,013filed Jan. 11, 2012, now U.S. Pat. No. 8,747,937, which is a NationalStage of PCT/JP2010/002869 filed Apr. 21, 2010, both of which areincorporated herein by reference. This application also claims thebenefit of JP 2009-109211 filed Apr. 28, 2009 and JP 2009-288155 filedDec. 18, 2009.

FIELD OF THE INVENTION

The present invention relates to a concentrated coffee extract solution.

BACKGROUND OF THE INVENTION

Aroma is an important factor in determining the preference of food anddrink, as its tastiness is an overall sensation of both taste and aroma.For example, coffee beverages are favorably and extensively consumed asa luxury grocery item. The flavor of each coffee beverage includesaroma, body, aftertaste and the like, and is characterized by roastedcoffee beans used upon production of a coffee extract solution.

The aroma of a coffee extract solution can be classified, from theviewpoint of volatility thereof, into three parts which are a top note,a middle note and a last note. The top note is low in boiling point andhigh in volatility, and includes aroma components perceivable first. Thelast note is high in boiling point and low in volatility, and includescomponents that play a role of a residual aroma. The middle note hasintermediate volatility and permanence between the top note and the lastnote, and includes components that play a central role of the aroma ofthe coffee extract solution.

As methods for collecting the top note out of these aroma components, itis known, for example, to have aroma components, which have vaporized asa result of heating of ground roasted coffee beans, carried by a carriergas and to capture them with an organic solvent (Patent Document 1), andalso to feed an ethanol-containing aqueous solution and an inert gasinto contact with heated, ground roasted coffee beans and to condenseand capture the resulting vaporized aroma components (Patent Document2). As a method for collecting the last note which takes a positionopposite to the top note, it has been proposed, for example, to subjecta coffee extraction residue, which remains after extraction of coffee,to steam extraction and to recover the distillate (Patent Document 3).As a method for using the top note and the last note, it has also beenproposed to blend an aroma solution, which has been obtained bycapturing aroma components released upon grinding roasted coffee beans,with a condensed residual-fragrance solution, which has been extractedwith an alkaline solution from a coffee extraction residue afterextraction of coffee (Patent Document 4). These conventional methods allcollect the top note from roasted coffee beans, and make no mentionabout its collection from a coffee extract solution.

With a view to avoiding reductions in taste and aroma due to a loss of aaroma component upon concentration of a coffee extract solution, on theother hand, a process has been proposed for the production of aconcentrated coffee extract solution (Patent Document 5). According tothis process, the coffee extract solution is concentrated through areverse osmosis membrane to separate it into a concentrated solution anda free solution after concentration (permeation solution), the freesolution after concentration is evaporated under reduced pressure toobtain from 3 to 25 wt % of a concentrated aroma solution, and theconcentrated aroma solution is then mixed with the concentratedsolution.

In recent years, as one of approaches for enhancing the preference ofcoffee beverages, a coffee beverage has been proposed (Patent Document6). To impart anew flavor (clarity), this coffee beverage makes use of acoffee extract solution which has been brought into contact with asynthetic adsorbent after its treatment with activated carbon.

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: JP-A-4-252153-   Patent Document 2: JP-A-6-276941-   Patent Document 3: JP-A-2000-135059-   Patent Document 4: JP-A-2004-201629-   Patent Document 5: JP-A-2003-319749-   Patent Document 6: JP-A-2007-282571

SUMMARY OF THE INVENTION

The present invention provides a concentrated coffee extract solutioncontaining the following components (A) and (B):

(A) at least one pyrazine selected from 2-methylpyrazine,2,5-dimethylpyrazine, 2,6-dimethylpyrazine, ethylpyrazine,2-ethyl-5-methylpyrazine, 2-ethyl-6-methylpyrazine,2-ethyl-3-methylpyrazine, 2-ethyl-3,5-dimethylpyrazine and3,5-dimethyl-2-methylpyrazine, and

(B) at least one guaiacol selected from guaiacol, 4-ethylguaiacol and4-vinylguaiacol,

wherein a content weight ratio [(B)/(A)] of the component (B) to thecomponent (A) is 0.6 or smaller.

The present invention also provides a soluble coffee which can beobtained by spray-drying or freeze-drying the concentrated coffeeextract solution, and also a packaged coffee beverage containing theconcentrated coffee extract solution.

The present invention further provides a process for producing aconcentrated coffee extract solution, which includes separating a coffeeextract solution into a concentrated solution and a fraction bydistillation, treating the concentrated solution with a porousadsorbent, and then mixing the concentrated solution, which has beentreated with the porous adsorbent, with the fraction.

DESCRIPTION OF THE INVENTION

As is known, a coffee extract solution obtained from roasted coffeebeans (arabica coffee from Brazil) has a flavor that has a rich sweetaroma but is insufficient in aftertaste.

With a view to further enhancing the preference of a coffee extractsolution obtained from roasted coffee beans (arabica coffee fromBrazil), the present inventors treated it by the method described inPatent Document 6 cited above. As a result, it was found that the sweetaroma characteristic to the roasted coffee beans was reduced althoughthe aftertaste-thereof was improved. Upon treatment of the coffeeextract solution, which had been obtained from the roasted coffee beans(arabica coffee from Brazil), by the process described in PatentDocument 5 cited above, on the other hand, it was found that the sweetaroma was enhanced but the aftertaste thereof still remained unimproved.

Under the assumption that the flavor of a coffee extract solution isbased on a subtle balance of a top note, a middle note and a last note,the present inventors therefore conducted a study on a coffee extractsolution from the viewpoint of flavor. As a result, it was found thatthe aroma of a coffee extract solution is characterized by a top noteand a middle note and that the taste of the coffee extract solution isclosely related to a last note. It was then found that a concentratedcoffee extract solution having a rich sweet aroma and a clean aftertastecan be obtained by controlling the content weight ratio of the specificaroma components, which are contained in the top note and middle note,to the specific aroma components, which are contained in the last note,to a predetermined range. It is to be noted that the term “aftertaste”as used herein means “a feeling that remains in the mouth” as defined inJIS Z 8144:2004.

According to the present invention, it is possible to provide aconcentrated coffee extract solution having a rich sweet aroma and aclear aftertaste. Further, the use of the concentrated coffee extractsolution makes it possible to provide a soluble coffee and packagedcoffee beverage, both of which have high preference.

(Concentrated Coffee Extract Solution)

The concentrated coffee extract solution according to the presentinvention contains (A) a pyrazine having a rich sweet aroma and (B) aguaiacol which is a causative substance that deteriorates theaftertaste, and the content of the guaiacol (B) has been significantlylowered. Owing to this feature, the abundance ratio of the pyrazine (A)in the concentrated coffee extract solution according to the presentinvention has been increased, and as a result, the concentrated coffeeextract solution has been enhanced in sweet aroma and has been improvedin aftertaste.

The term “the pyrazine (A)” is a concept that embraces 2-methylpyrazine,2,5-dimethylpyrazine, 2,6-dimethylpyrazine, ethylpyrazine,2-ethyl-5-methylpyrazine, 2-ethyl-6-methylpyrazine,2-ethyl-3-methylpyrazine, 2-ethyl-3,5-dimethylpyrazine and3,5-dimethyl-2-methylpyrazine, and is needed to include at least one ofthem in the present invention. It is to be noted that the content of thepyrazine (A) in the concentrated coffee extract solution according tothe present invention is defined based on the total amount of theabove-described nine pyrazines.

Also, the term “the guaiacol (B)” is a concept that encompassesguaiacol, 4-ethylguaiacol and 4-vinylguaiacol, and is needed to includeat least one of them in the present invention. It is to be noted thatthe content of the guaiacol (B) in the concentrated coffee extractsolution according to the present invention is defined based on thetotal amount of the above-described three guaiacols.

The content weight ratio [(B)/(A)] of the component (B) to the component(A) in the concentrated coffee extract solution according to the presentinvention is 0.6 or smaller. From the viewpoints of enhancing the sweetaroma and improving the aftertaste, the lower the weight ratio[(B)/(A)], the more preferred. Described specifically, the weight ratio[(B)/(A)] may be preferably 0.55 or smaller, more preferably 0.5 orsmaller, more preferably 0.45 or smaller, more preferably 0.4 orsmaller, even more preferably 0.35 or smaller. It is to be noted that inthis specification, a method for the measurement of the content weightratio [(B)/(A)] of the component (B) to the component (A) shall be basedon the “Analysis method of pyrazines and guaiacols” in Examples to bedescribed subsequently herein. The lower limit of the weight ratio[(B)/(A)] is not limited specifically, and may be even 0. From theviewpoint of production efficiency, the weight ratio [(B)/(A)] may bepreferably 0.0001 or greater, more preferably 0.001 or greater.

The concentrated coffee extract solution according to the presentinvention may contain (C) a chlorogenic acid, and from the viewpoints offlavor balance and physiological effects, the content of the chlorogenicacid (C) in the concentrated coffee extract solution according to thepresent invention may be preferably from 0.01 to 5 wt %, more preferablyfrom 0.02 to 3 wt %, more preferably from 0.03 to 2 wt %, even morepreferably from 0.05 to 1.5 wt %. It is to be noted that the term “thechlorogenic acid” is a generic term that collectively encompasses, asmonocaffeoylquinic acids, 3-caffeoylquinic acid, 4-caffeoylquinic acidand 5-caffeoylquinic acid; as monoferuloylquinic acids, 3-feruloylquinicacid, 4-feruloylquinic acid and 5-feruloylquinic acid; and asdicaffeoylquinic acids, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinicacid and 4,5-dicaffeoylquinic acid. The content of the chlorogenic acidis defined based on the total amount of the above-described ninechlorogenic acids.

The concentrated coffee extract solution according to the presentinvention may also contain (D) hydroxyhydroquinone. The content of (D)hydroxyhydroquinone in the concentrated coffee extract solutionaccording to the present invention may be preferably lower than 0.1 wt%, more preferably lower than 0.08 wt %, more preferably lower than 0.06wt %, even more preferably lower than 0.04 wt % based on the content ofthe chlorogenic acid, from the viewpoints of flavor balance andphysiological effects. On the other hand, its lower limit is not limitedspecifically and may be even 0 wt %.

As a form of the concentrated coffee extract solution according to thepresent invention, it may include various forms such as an aqueoussolution, solid (e.g., dried product), liquid and slurry (e.g.,concentrate), and may be chosen as desired.

(Production Process of Concentrated Coffee Extract Solution)

A description will next be made about a process for the production ofthe concentrated coffee extract solution according to the presentinvention.

First, a coffee extract solution to be used as a raw material isprovided.

The coffee extract solution may be extracted from roasted coffee beans,or be prepared from an aqueous solution or the like of an instantcoffee. The coffee extract solution for use in the present invention maybe one obtained by using preferably 1 g or more, more preferably 2.5 gor more, even more preferably 5 g or more of coffee beans in terms ofgreen beans per 100 g of the coffee extract solution.

As a species of the coffee beans for use in the present invention,Arabica species, Robusta species and the like may be exemplified. Asvarieties of coffee beans, it may include Brazil, Colombia, Tanzania,Mocha, Kilimanjaro, Mandarin, Blue Mountain and the like. These coffeebeans may be used as a single variety, or plural varieties may be usedas a blend. Among these, arabica coffee from Brazil is preferred ascoffee beans from the viewpoint of flavor balance.

As a method for roasting the coffee beans, it is possible to suitablychoose a known method such as, for example, the direct-fired method, thehot-air method, or the half-hot-air method. It is preferred to include arotary drum in such a roasting method. The roasting temperature is notspecifically limited, and it may be preferably from 100 to 300° C., morepreferably from 150 to 250° C. From the viewpoint of taste and aroma,the roasted coffee beans may be cooled preferably to from 0 to 100° C.,more preferably from 10 to 60° C. within one hour after the roasting.

Concerning the degree of roast of roasted coffee beans, light, cinnamon,medium, high, city, full-city, French and Italian may be exemplified. Ofthese, preferred is light, cinnamon, medium, high, and city.

The L value available from the measurement of the degree of roast by acolor difference meter may be preferably from 10 to 35, more preferablyfrom 15 to 25, even more preferably from 16 to 25. It is to be notedthat in the present invention, coffee beans having different degrees ofroast may be mixed or may be used after grinding.

No particular limitation is imposed on the manner of extraction fromroasted coffee beans, and as an illustrative manner, extraction may beconducted for from 10 seconds to 30 minutes from the roasted coffeebeans or coffee grounds thereof with an extraction solvent such as coldwater to hot water (0 to 100° C.). Concerning the fineness of grind,extra-fine grind (0.250 to 0.500 mm), fine grind (0.300 to 0.650 mm),medium-fine grind (0.530 to 1.000 mm), medium grind (0.650 to 1.500 mm),medium-coarse grind, coarse grind (0.850 to 2.100 mm), and extra-coarsegrind (1.000 to 2.500 mm) may be mentioned, or cut coffees of approx. 3mm, 5 mm or 10 mm in average cut size may be mentioned. As extractionmethods, boiling, espresso, siphon, drip (with paper, flannel or thelike), and the like may be mentioned.

The extraction solvent may be water, alcohol-containing water, milk,carbonated water or the like. The pH (25° C.) of the extraction solventmay be generally from 4 to 10, with from 5 to 7 being preferred from theviewpoint of taste and aroma. A pH regulator, for example, sodiumbicarbonate, sodium hydrogencarbonate, L-ascorbic acid or sodiumL-ascorbate may be incorporated in the extraction solvent to adjust itspH as desired.

No particular limitation is imposed on an extractor. Illustrative are aheated pot, a stirrer-equipped pot and stirred pot, a bag-shapedstructure made of paper or nonwoven fabric and suspendable practicallyinto a coffee cup, a drip brewer equipped in an upper part thereof witha spray nozzle and in a lower part thereof with a structure (a mesh orpunched metal and the like) capable of practically performing asolid-liquid separation of coffee beans, and a column extractor equippedin upper and lower parts thereof with structures (meshes or punchedmetals and the like) capable of practically performing a solid-liquidseparation of coffee beans, and the like. These extractors and brewermay be equipped with a structure that permits heating or cooling (forexample, an electric heater, or a jacket through which hot water, steamor cold water can be passed).

As extraction processes, batchwise extraction process, semi-batchwiseextraction and continuous extraction may be mentioned. The extractiontime of the batchwise extraction or semi-batchwise extraction may bepreferably from 10 seconds to 120 minutes, more preferably from 30seconds to 40 minutes from the viewpoint of taste and aroma.

In the present invention, the coffee extract solution obtained byextraction from the roasted coffee beans may be used as it is. Thesolids content of the coffee extract solution may be preferably from 1to 10%, more preferably from 2 to 7%, even more preferably 3% or higherbut lower than 5%. The term “solids content” as used herein means onemeasured by the “Measurement method of Brix degree” in Example to bedescribed subsequently herein.

The coffee extract solution is next distilled. By the distillation, thecoffee extract solution is separated into a fraction and a concentratedsolution. The fraction contains a portion of the middle note and the topnote, while the concentrated solution contains a portion of the middlenote and the last note. For example, effective aroma components such asthe pyrazine (A) are recovered in the fraction, while unnecessarycomponents such as the guaiacol (B) are recovered in the concentratedsolution.

To distil the coffee extract solution, distillation may be conducted bya known method and equipment, and no particular limitation is imposed onthe distillation method or equipment.

From the viewpoints of the capture of aroma components, separation rateand the like, the distillation may desirably be conducted under areduced pressure of preferably from 5 to 100 kPa, more preferably from10 to 50 kPa, more preferably from 10 to 40 kPa, even more preferablyfrom 10 to 30 kPa in absolute pressure.

As a temperature condition for the distillation, the distillationtemperature may be preferably 20° C. or higher, more preferably 30° C.or higher, more preferably 35° C. or higher, more preferably 40° C. orhigher, even more preferably 55° C. or higher from the viewpoints of thecapture of aroma components and the assurance of an evaporation rate.From the viewpoint of the quality maintenance of the concentrated coffeeextract solution, on the other hand, the distillation temperature may bepreferably 100° C. or lower, more preferably 80° C. or lower, even morepreferably 70° C. or lower.

From the viewpoint of having unnecessary components such as the guaiacol(B) and hydroxyhydroquinone efficiently adsorbed on a porous adsorbentand allowing aroma components to move sufficiently into a fraction whilesuppressing the adsorption of the aroma components, the weight ratio ofthe fraction to the coffee extract solution may be preferably from 0.3to 0.9, more preferably from 0.4 to 0.85, even more preferably from 0.5to 0.8.

The concentrated solution separated as described above is next treatedwith the porous adsorbent. By this treatment, the unnecessary componentssuch as the guaiacol (B) and hydroxyhydroquinone contained in the lastnote can be eliminated.

As the kind of the porous adsorbent for use in the present invention, itis possible to use one of the carbonaceous adsorbents,silica/alumina-based adsorbents, polymer adsorbents, chitosan resins andthe like, which are described in “Adsorption TechnologyHandbook—Process, Material, Design” in Japanese (Published on Jan. 11,1999 by NTS Inc., Editor: Y. TAKEUCHI). Among these, the carbonaceousadsorbents are preferred from the viewpoint of efficient elimination ofunnecessary substances.

Of the carbonaceous adsorbents, powdery activated carbon, granularactivated carbon and activated carbon fibers are preferred from theviewpoint of efficient elimination of unnecessary substances.

Source materials for powdery and granular activated carbons include sawdust, coal, palm shells, and the like. Preferred is the palm shellactivated carbon derived from palm shells, with activated carbonactivated with a gas such as steam being more preferred. As commercialproducts of such steam-activated, activated carbon, “SHIRASAGI WH2c”(Japan EnviroChemicals, Ltd.), “TAIKO CW” (Futamura Chemical IndustriesCo., Ltd.), “KURARAY COAL GL” (Kuraray Chemical Co., Ltd.) and the likemay be used.

The amount of the porous adsorbent to be used may be preferably from 0.1to 2 weight times, more preferably from 0.2 to 1 weight times, morepreferably from 0.3 to 0.8 weight times, even more preferably from 0.4to 0.7 weight times relative to the solids content of the concentratedsolution, from the viewpoint of efficient elimination of unnecessarycomponents.

A contact treatment method may be a batch method or a columnpass-through method.

As the batch method, the porous adsorbent may be added to theconcentrated solution and after stirring it at from −10 to 100° C. forfrom 0.5 minute to 5 hours, the adsorbent may be removed. An atmosphereat the time of the treatment may be air or an inert gas (nitrogen gas,argon gas, helium gas, or carbon dioxide), with an inert gas beingpreferred from the viewpoint of taste and aroma.

As the column pass-through method, the adsorbent may be packed in anadsorption column, and the concentrated solution may be charged from alower part or upper part of the column and discharged from the oppositepart. The ratio L/D of the pack height L to D (diameter) for theadsorbent may preferably be from 0.1 to 10. The amount of the adsorbentto be packed in the column may be such that the adsorbent can be packedin the adsorption column before pass-through. The adsorption column ispreferably equipped, in at least one of its upper stage and lower stage,with a separation structure that can substantially prevent the adsorbentfrom flowing out, such as a mesh (screen) or punched metal. Noparticular limitation is imposed on the opening size of the separationstructure, insofar as it is smaller than the average particle size ofthe adsorbent. The separation structure may have apertures of preferably½ or smaller, more preferably ⅓ or smaller of the average particle sizeof the adsorbent. The specific opening size may preferably be from 0.1to 1,000 μm.

The adsorption treatment temperature of the concentrated solution may bepreferably from −10° C. to 100° C., more preferably from 0 to 40° C.from the viewpoint of taste and aroma. The residence time (K/QC) of theflow quantity (QC [g/min]) of the concentrated solution relative to theamount (K[g]) of the adsorbent in the adsorption column may preferablybe from 0.5 to 300 minutes.

The concentrated solution treated with the porous adsorbent and thefraction are next mixed together. Upon conducting this mixing, themixing ratio of the concentrated solution treated with the porousadsorbent to the fraction is adjusted such that the weight ratio[(B)/(A)] falls within the above-described range. The fraction may beused as it is, or may be concentrated or diluted as needed.

In the fraction, effective aroma components such as the pyrazine (A) areabundantly contained, while the guaiacol (B) which is a causativesubstance that deteriorates the aftertaste is not contained practically.Owing to the treatment with the porous adsorbent, the content of theguaiacol (B) has been lowered significantly in the concentrated solutiontreated with the porous adsorbent. By mixing the concentrated solution,which has been treated with the porous adsorbent, with the fraction suchthat the weight ratio [(B)/(A)] falls within the above-described range,a concentrated coffee extract solution can be obtained with a rich sweetaroma and clean aftertaste.

(Soluble Coffee, Packaged Coffee Beverage)

The concentrated coffee extract solution according to the presentinvention is suited for the production of a soluble coffee and packagedcoffee beverage.

The soluble coffee according to the present invention can be obtained bydrying the concentrated coffee extract solution. As a drying method,spray drying, freeze drying or the like may be exemplified. As a form ofthe soluble coffee, a powder, granules, tablets or the like may beexemplified.

Also, the packaged coffee beverage according to the present inventioncan be produced by filling the concentrated coffee extract solution, asit is, in a package or by filling it in a package after concentration ordilution as needed.

In the packaged coffee beverage according to the present invention, oneor more of additives may be added as needed. These additives may includebitterness suppressors, antioxidants, flavor, various esters, organicacids, organic acid salts, inorganic acids, inorganic acid salts,inorganic salts, colorants, emulsifiers, preservatives, seasoningagents, sour seasonings, quality stabilizers, and so on. The packagedcoffee beverage according to the present invention may be produced as apackaged black coffee beverage or a packaged milk coffee beverage.

The packaged coffee beverage according to the present invention maypreferably contain the chlorogenic acid (C) at preferably from 0.01 to 1wt %, more preferably from 0.05 to 0.5 wt %, even more preferably from0.1 to 0.3 wt %.

Also, in the soluble coffee according to the present invention, thelower limit of the chlorogenic acid (C) may be preferably 5 wt % orhigher, more preferably 8 wt % or higher, more preferably 10 wt % orhigher, even more preferably 12 wt % or higher, while its upper limitmay be preferably 25 wt % or lower, more preferably 20 wt % or lower,more preferably 18 wt % or lower, even more preferably 16 wt % or lower.

In the soluble coffee and packaged coffee beverage according to thepresent invention, the content of hydroxyhydroquinone (D) may bepreferably less than 0.1 wt. %, more preferably less than 0.05 wt %,more preferably less than 0.03 wt %, even more preferably less than 0.01wt % based on the content of the chlorogenic acid, while the lower limitis not particularly limited and may be even 0 wt %.

The packaged coffee beverage according to the present invention can beprovided in a conventional package such as a molded package made ofpolyethylene terephthalate as a principal component (a so-called PETbottle), a metal can, a paper package combined with metal foils orplastic films, a bottle or the like.

The packaged beverage can be produced, for example, by filling thebeverage in a package like a metal can and after that, when heatsterilization is feasible, conducting the heat sterilization understerilization conditions prescribed in relevant regulations (in Japan,the Food Sanitation Act). For those which cannot be subjected to retortsterilization like PET bottles or paper packages, a process may beadopted such that the beverage is sterilized beforehand at a hightemperature for a short time under similar sterilization conditions asthose described above, for example, by a plate-type heat exchanger orthe like, is cooled to a particular temperature, and is then filled in apackage.

EXAMPLES

(Analysis of Chlorogenic Acids)

An analysis method of chlorogenic acids was as will be describedhereinafter. HPLC was used as an analyzer.

The followings are the model numbers of component units in the analyzer.

-   -   UV-VIS detector: “L-2420” (Hitachi High-Technologies        Corporation)    -   Column oven: “L-2300” (Hitachi High-Technologies Corporation)    -   Pump: “L-2130” (Hitachi High-Technologies Corporation)    -   Autosampler: “L-2200” (Hitachi High-Technologies Corporation)    -   Column: “CADENZA CD-C18”, 4.6 mm inner diameter×150 mm length,        particle size: 3 μm (Intact Corp.)

Analytical conditions were as follows.

-   -   Sample injection volume: 10 μL    -   Flow rate: 1.0 mL/min    -   Wavelength preset for UV-VIS detector: 325 nm    -   Preset column-oven temperature: 35° C.    -   Eluent A: 5 (V/V) % acetonitrile solution containing 0.05 M of        acetic acid, 0.1 mM 1-hydroxyethane-1,1-diphosphonic acid and 10        mM sodium acetate    -   Eluent B: acetonitrile        Concentration Gradient Conditions

Time Eluent A Eluent B  0.0 min 100% 0% 10.0 min 100% 0% 15.0 min 95% 5%20.0 min 95% 5% 22.0 min 92% 8% 50.0 min 92% 8% 52.0 min 10% 90% 60.0min 10% 90% 60.1 min 100% 0% 70.0 min 100% 0%

In HPLC, a sample (1 g) was accurately weighed, its total volume wasincreased to 10 mL with Eluent A, and subsequent to filtration through amembrane filter (“GL CHROMATODISK 25A”, pore size: 0.45 μm, GL Science,Inc.), the filtrate was provided for an analysis.

Retention time (unit:min) of chlorogenic acids, i.e., nine chlorogenicacids:

(C¹) Monocaffeoylquinic acids: 3 kinds at 5.3, 8.8 and 11.6 in total

(C²) Feruloylquinic acids: 3 kinds at 13.0, 19.9 and 21.0 in total

(C³) Dicaffeoylquinic acids: 3 kinds at 36.6, 37.4 and 44.2 in total

From the area values of the nine chlorogenic acids as determined above,the wt % of the chlorogenic acids was determined by using5-caffeoylquinic acid as a standard substance.

(Analysis of Hydroxyhydroquinone)

An analytical method of hydroxyhydroquinone was as will be describedhereinafter.

As an analyzer, an HPLC-electrochemical detector (the coulometric type)“COULARRAY SYSTEM” (model: 5600A, developed and manufactured by: ESAAnalytical, Ltd., U.S.A., imported and sold by: MC Medical, Inc.) wasused.

The followings are the names and model numbers of component units in theanalyzer.

-   -   Analytical cell: “MODEL 5010”, coularray organizer, coularray        electronics module,    -   Software: “MODEL 5600A”    -   Solvent feeder module: “MODEL 582”, gradient mixer    -   Autosampler: “MODEL 542”, pulse damper    -   Degasser: “DEGASYS ULTIMATE DU3003”    -   Column oven: “505”    -   Column: “CAPCELL PAK C18 AQ”, 4.6 mm inner diameter×250 mm        length, particle size: 5 μm (Shiseido Co., Ltd.)

Analytical conditions were as follows.

-   -   Sample injection volume: 10 μL    -   Flow rate: 1.0 mL/min    -   Voltage applied to electrochemical detector: 0 mV,    -   Preset column-oven temperature: 40° C.    -   Eluent C: 5 (V/V) % methanol solution containing 0.1 (W/V) %        phosphoric acid and 0.1 mM 1-hydroxyethane-1,1-diphosphonic acid    -   Eluent D: 50 (V/V) % methanol solution containing 0.1 (W/V) %        phosphoric acid and 0.1 mM 1-hydroxyethane-1,1-diphosphonic acid

For the preparation of Eluents C and D, distilled water forhigh-performance liquid chromatography (Kanto Chemical Co., Ltd.),methanol for high-performance liquid chromatography (Kanto Chemical Co.,Ltd.), phosphoric acid (guaranteed reagent, Wako Pure ChemicalIndustries, Ltd.) and 1-hydroxyethane-1,1-diphosphonic acid (60% aqueoussolution, Tokyo Kasei Kogyo Co., Ltd.) were used.

Concentration Gradient Conditions

Time Eluent C Eluent D  0.0 min 100% 0% 10.0 min 100% 0% 10.1 min 0%100% 20.0 min 0% 100% 20.1 min 100% 0% 50.0 min 100% 0%

For the preparation of each analysis sample, a sample (5 g) wasaccurately weighed, its total volume was increased to 10 mL with a 5(V/V) % methanol solution containing 0.5 (W/V) % phosphoric acid and 0.5mM 1-hydroxyethane-1,1-diphosphonic acid. The solution was subjected toa centrifugation to obtain a supernatant. The supernatant was allowed topass through “BOND ELUTE SCX” (packed weight of solid phase: 500 mg,reservoir capacity: 3 mL, GL Science, Inc.), and an initial volume(approx. 0.5 mL) of passed solution was diverted to obtain a passedsolution. The passed solution was subjected to filtration through amembrane filter (“GL CHROMATODISK 25A”, pore size: 0.45 μm, GL Science,Inc.), and the filtrate was promptly provided for its analysis.

In the analysis by the HPLC-electrochemical detector under theabove-described conditions, the retention time of hydroxyhydroquinonewas 6.38 minutes. From the area value of the resulting peak, its % byweight was determined by using hydroxyhydroquinone (Wako Pure ChemicalIndustries, Ltd.) as a standard substance.

(Analyses of Pyrazines and Guaiacols)

A sample (2 g) was sampled in a vial. Aroma components in a headspacewere adsorbed by an SPME fiber and were provided for GC/MS measurement.From the area values of the pyrazines and guaiacols, the weight ratio{(B)/(A)} was determined.

Analytical conditions were as follows.

HS-GC/MS Conditions

-   -   Measurement instrument: “HP6890” (manufactured by Agilent        Technologies, Inc.)    -   Column: “BC-WAX”, 0.25 mm inner diameter×50 mm    -   length, particle size: 0.25 μm (GL Science, Inc.)    -   Temperature program: 60° C. (5 min)->230° C., heated at 5°        C./min    -   Head pressure: 14.8 psi    -   Inlet temperature: 210° C.    -   Detector temperature: 200° C.    -   Split ratio: 30:1    -   Carrier gas: helium    -   Scan mode: Ionization voltage 70 eV        (Measurement of Brix Degree)

It was indicated as a sugar refractometer index (Brix degree) at 20° C.The measurement was conducted by “ATAGO RX-5000” (manufactured by AtagoCo., Ltd.).

(Sensory Evaluation)

Each packaged coffee beverage was tested by a panel of five experts, andwith respect to (i) sweet aroma and (ii) aftertaste, evaluations weremade in accordance with the following standards. Subsequently, finalscores were determined upon deliberation.

(i) Evaluation Standards for Sweet Aroma

A: A sweet aroma is strong.

B: A sweet aroma is a little strong.

C: A sweet aroma is a little weak.

D: A sweet aroma is weak.

(ii) Evaluation Standards for Aftertaste

A: Clear.

B: A little clear.

C: A little dull.

D: Dull.

Example 1

(Preparation of Coffee Extract Solution)

Roasted coffee beans (arabica coffee from Brazil, a 58/42 blend ofcoffee beans roasted to L34/L16.5 degrees of roast, 400 g) wereextracted with hot water of 93° C. to obtain a coffee extract solution(2,400 g).

The analytical values of respective components in the resultant coffeeextract solution were as follows.

Brix degree (%): 4.76

Chlorogenic acids (CGA) (mg/100 g): 437.9

Hydroxyhydroquinone (HHQ) (mg/kg): 22.12

(Distillation of Coffee Extract Solution)

The coffee extract solution (2,318 g, solids content: 4.75%) wasconcentrated at 60° C. under a reduced pressure of 18.7 kPa, and afraction was condensed at a solution temperature of 8° C. to obtain 32.2wt % of a concentrated solution (solids content: 14.28%) and 67.8 wt %of a fraction (solids content: 0.22%).

(Treatment of Concentrated Solution with Activated Carbon)

Only the concentrated solution was treated at 25° C. with activatedcarbon (“SHIRASAGI WH2C 42/80LSS”, Japan EnviroChemicals, Ltd.). Theamount of the activated carbon to be used was set at 0.5 weight timesrelative to the solids content of the concentrated solution.

(Mixing of Concentrated Solution Treated with Activated Carbon, withFraction)

The resultant, concentrated solution treated with activated carbon (732g, solids content: 10.9%) and the fraction (1,570 g, solids content:0.22%) were mixed in their entirety to obtain a concentrated coffeeextract solution.

(Packaged Coffee Beverage)

The resultant, concentrated coffee extract solution was diluted andadjusted with deionized water to a Brix degree of 1.85. After beingfilled in a can package, heat sterilization was conducted at 134° C. for90 seconds to obtain a packaged coffee beverage. The resultant, packagedcoffee beverage was then subjected to a componential analysis and asensory test. The production conditions for the concentrated coffeeextract solution are shown in Table 1, and the results of thecomponential analysis and sensory test are presented in Table 2.

Example 2

A packaged coffee beverage was obtained in a similar manner as inExample 1, except that the distillation of the coffee extract solutionwas conducted at 50° C. under a reduced pressure of 34.7 kPa and 54.8 wt% of the concentrated solution and 45.2 wt % of the fraction were used.The resultant, packaged coffee beverage was then subjected to acomponential analysis and a sensory test. The production conditions forthe concentrated coffee extract solution are shown in Table 1, and theresults of the componential analysis and sensory test are presented inTable 2.

Example 3

A packaged coffee beverage was obtained in a similar manner as inExample 1, except that in the treatment of the concentrated solutionwith the activated carbon, the amount of the activated carbon to be usedwas changed to 0.25 weight times relative to the solids content of theconcentrated solution. The resultant, packaged coffee beverage was thensubjected to a componential analysis and a sensory test. The productionconditions for the concentrated coffee extract solution are shown inTable 1, and the results of the componential analysis and sensory testare presented in Table 2.

Comparative Example 1

A packaged coffee beverage was obtained in a similar manner as inExample 1, except that the treatment with activated carbon was notconducted on the concentrated solution. The resultant, packaged coffeebeverage was then subjected to a componential analysis and a sensorytest. The production conditions for the concentrated coffee extractsolution are shown in Table 1, and the results of the componentialanalysis and sensory test are presented in Table 2.

Comparative Example 2

A packaged coffee beverage was obtained in a similar manner as inExample 1, except that the coffee extract solution was subjected totreatment with activated carbon as it is without distillation. Theresultant, packaged coffee beverage was then subjected to a componentialanalysis and a sensory test. The production conditions for the coffeeextract solution are shown in Table 1, and the results of thecomponential analysis and sensory test are presented in Table 2.

Comparative Example 3

Roasted coffee beans (arabica coffee from Brazil, a 58/42 blend ofcoffee beans roasted to L34/L16.5 degrees of roast, 400 g) wereextracted with hot water of 93° C. to obtain a coffee extract solution(2,400 g). The coffee extract solution was diluted and adjusted withdeionized water to a Brix degree of 1.85. After being filled in a canpackage, heat sterilization was conducted at 134° C. for 90 seconds toobtain a packaged coffee beverage. The resultant, packaged coffeebeverage was then subjected to a componential analysis and a sensorytest. The production conditions for the concentrated coffee extractsolution are shown in Table 1, and the results of the componentialanalysis and sensory test are presented in Table 2.

TABLE 1 Production Conditions for Concentrated Coffee Extract SolutionsExample Comparative Example 1 2 3 1 2 3 <Concentration> Temperature (°C.) 60 50 60 60 — — Pressure (kPa) 18.7 34.7 18.7 18.7 — —Fraction/coffee extract 67.8 45.2 67.8 67.8 — — solution (wt %)Concentrated 32.2 54.8 32.2 32.2 — — solution/coffee extract solution(wt %) Brix degree of concentrated 14.3 8.7 14.3 14.3 — — solution (%)Treatment with activated Treated Treated Treated Not Treated Not carbontreated treated Amount of activated carbon to 0.5 0.5 0.25 — 0.5 — beused (relative to the solids content of concentrated solution) <Recoveryof fraction> Recovery of fraction Recovered Recovered RecoveredRecovered Not Not recovered recovered Brix degree after recovery of 1.851.84 1.85 1.85 1.85 1.85 fraction and dilution (%)

TABLE 2 Componential Analysis and Sensory Evaluation of ConcentratedCoffee Extract Solutions Example Comparative Example 1 2 3 1 2 3(A)Pyrazines (Area × 10⁷) 2-Methylpyrazine 0.99 0.46 0.90 0.75 0.09 1.072,5-Dimethylpyrazine 0.64 0.24 0.55 0.55 0.05 0.73 2,6-Dimethylpyrazine0.55 0.33 0.49 0.51 0.07 0.69 Ethylpyrazine 0.45 0.24 0.37 0.34 0.050.46 2-Ethyl-5-methylpyrazine 0.70 0.41 0.57 0.59 0.08 0.812-Ethyl-6-methylpyrazine 0.58 0.34 0.48 0.49 0.07 0.632-Ethyl-3-methylpyrazine 0.49 0.30 0.43 0.50 0.06 0.642-Ethyl-3,5-dimethylpyrazine 0.98 0.60 1.02 1.13 0.12 1.423,5-Dimethyl-2-methylpyrazine 0.31 0.15 0.25 0.26 0.03 0.40 Total (Areas× 10⁷) 5.69 3.07 5.06 5.12 0.62 6.85 (B)Guaiacols (Area × 10⁷) Guaiacol0.39 0.26 0.34 0.42 0.08 0.55 4-Ethylguaiacol 0.66 0.40 0.60 0.90 0.181.07 4-Vinylguaiacol 0.78 0.51 0.97 2.34 0.47 2.94 Total (Areas × 10⁷)1.83 1.17 1.91 3.66 0.73 4.56 Weight ratio (B)/(A) 0.32 0.38 0.38 0.711.18 0.67 (C) Chlorogenic acids (wt %) 0.19 0.19 0.18 0.17 0.18 0.17 (D)Hydroxyhydroquinone (wt %) 0.000032 0.000033 0.000040 0.00086 0.0000400.00086 Sensory evaluation Sweet aroma A B A A D B Aftertaste A A B D AD

From Table 2, it has found that a packaged coffee beverage having a richsweet aroma and clear aftertaste can be obtained by adding aconcentrated coffee extract solution in which the content weight ratio[(B)/(A)] of (B) a guaiacol to (A) a pyrazine has been controlled to apredetermined range.

The invention claimed is:
 1. A process for producing a concentratedcoffee extract solution, the process comprising: separating a coffeeextract solution into a concentrated solution and a fraction comprisingpyrazine by distillation, wherein a weight ratio of the fraction to theinitial coffee extract solution is from 0.3 to 0.9 treating theconcentrated solution with a porous adsorbent, thereby absorbing atleast some guaiacol and/or hydroxyhydroquinone, and then mixing theconcentrated solution, which has been treated with the porous adsorbent,with the fraction.
 2. The process according to claim 1, wherein acontent of solids in the coffee extract solution is from 1 to 10%. 3.The process according to claim 1, wherein the coffee extract solution isdistilled at from 20 to 100° C. under a reduced pressure of from 5 to100 kPa.
 4. The process according to claim 2, wherein the coffee extractsolution is distilled at from 20 to 100° C. under a reduced pressure offrom 5 to 100 kPa.
 5. The process according to claim 1, wherein theporous adsorbent is used in an amount of from 0.1 to 2 weight timesrelative to a content of solids in the concentrated solution.
 6. Theprocess according to claim 2, wherein the porous adsorbent is used in anamount of from 0.1 to 2 weight times relative to a content of solids inthe concentrated solution.
 7. The process according to claim 3, whereinthe porous adsorbent is used in an amount of from 0.1 to 2 weight timesrelative to a content of solids in the concentrated solution.
 8. Theprocess according to claim 4, wherein the porous adsorbent is used in anamount of from 0.1 to 2 weight times relative to a content of solids inthe concentrated solution.
 9. The process of claim 1, wherein the mixingof the concentrated solution with the fraction produces a coffee extractsolution wherein a content weight ratio [(B)/(A)] of at least oneguaiacol (B) to at least one pyrazine (A) is from 0.0001 to 0.6.
 10. Theprocess of claim 1, wherein the mixing of the concentrated solution withthe fraction produces a coffee extract solution wherein a content weightratio [(B)/(A)] of at least one guaiacol (B) to at least one pyrazine(A) is from 0.001 to 0.35.
 11. The process of claim 1, wherein theweight ratio of the fraction to the initial coffee extract solution isfrom 0.4 to 0.9.
 12. The process of claim 1, wherein the weight ratio ofthe fraction to the initial coffee extract solution is from 0.5 to 0.9.